Tag: Networked Storage

Is the Sun Setting on Some of Your Technologies?

Tom Friend Leave a comment

So much of what we discuss within SNIA is the latest emerging technologies in storage. While it’s good to know about what technology is coming, it’s also important to understand the technologies that should be sunsetted.

It’s the topic of our next SNIA Networking Storage Forum (NSF) webcast on February 3, 2021, “Storage Technologies & Practices Ripe for Refresh.”  In this webcast, you’ll learn about storage technologies and practices in your data center that are ready for refresh or possibly retirement. Find out why some long-standing technologies and practices should be re-evaluated. We’ll discuss:

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Hyperscalers Take on NVMe™ Cloud Storage Questions

J Metz Leave a comment

Our recent webcast on how Hyperscalers, Facebook and Microsoft are working together to merge their SSD drive requirements generated a lot of interesting questions. If you missed “How Facebook & Microsoft Leverage NVMe Cloud Storage” you can watch it on-demand. As promised at our live event. Here are answers to the questions we received.

Q. How does Facebook or Microsoft see Zoned Name Spaces being used?

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The Blurred Lines of Memory and Storage – A Q&A

John Kim 1 Comment

The lines are blurring as new memory technologies are challenging the way we build and use storage to meet application demands. That’s why the SNIA Networking Storage Forum (NSF) hosted a “Memory Pod” webcast is our series, “Everything You Wanted to Know about Storage, but were too Proud to Ask.” If you missed it, you can watch it on-demand here along with the presentation slides  we promised.

Q. Do tools exist to do secure data overwrite for security purposes?

A. Most popular tools are cryptographic signing of the data where you can effectively erase the data by throwing away the keys. There are a number of technologies available; for example, the usual ones like BitLocker (part of Windows 10, for example) where the NVDIMM-P is tied to a specific motherboard. There are others where the data is encrypted as it is moved from NVDIMM DRAM to flash for the NVDIMM-N type. Other forms of persistent memory may offer their own solutions. SNIA is working on a security model for persistent memory, and there is a presentation on our work here.

Q. Do you need to do any modification on OS or application to support Direct Access (DAX)?

A. No, DAX is a feature of the OS (both Windows and Linux support it). DAX enables direct access to files stored in persistent memory or on a block device. Without DAX support in a file system, the page cache is generally used to buffer reads and writes to files, and DAX avoids that extra copy operation by performing reads and writes directly to the storage device.

Q. What is the holdup on finalizing the NVDIMM-P standard? Timeline?

A. The DDR5 NVDIMM-P standard is under development.

Q. Do you have a webcast on persistent memory (PM) hardware too?

A. Yes. The snia.org website has an educational library with over 2,000 educational assets. You can search for material on any storage-related topic. For instance, a search on persistent memory will get you all the presentations about persistent memory.

Q. Must persistent memory have Data Loss Protection (DLP)

A. Since it’s persistent, then the kind of DLP is the kind relevant for other classes of storage. This presentation on the SNIA Persistent Memory Security Threat Model covers some of this.

Q. Traditional SSDs are subject to “long tail” latencies, especially as SSDs fill and writes must be preceded by erasures. Is this “long-tail” issue reduced or avoided in persistent memory?

A. As PM is byte addressable and doesn’t require large block erasures, the flash kind of long tail latencies will be avoided. However, there are a number of proposed technologies for PM, and the read and write latencies and any possible long tail “stutters” will depend on their characteristics.

Q. Does PM have any Write Amplification Factor (WAF) issues similar to SSDs?

A. The write amplification (WA) associated with non-volatile memory (NVM) technologies comes from two sources.

  1. When the NVM material cannot be modified in place but requires some type of “erase before write” mechanism where the erasure domain (in bytes) is larger than the writes from the host to that domain.
  2. When the atomic unit of data placement on the NVM is larger than the size of incoming writes. Note the term used to denote this atomic unit can differ but is often referred to as a page or sector.

NVM technologies like the NAND used in SSDs suffer from both sources 1 and 2. This leads to very high write amplification under certain workloads, the worst being small random writes. It can also require over provisioning; that is, requiring more NVM internally than is exposed to the user externally.

Persistent memory technologies (for example Intel’s 3DXpoint) only suffer from source 2 and can in theory suffer WA when the writes are small. The severity of the write amplification is dependent on how the memory controller interacts with the media. For example, current PM technologies are generally accessed over a DDR-4 channel by an x86 processor. x86 processors send 64 bytes at a time down to a memory controller, and can send more in certain cases (e.g. interleaving, multiple channel parallel writes, etc.). This makes it far more complex to account for WA than a simplistic random byte write model or in comparison with writing to a block device.

Q. Persistent memory can provide faster access in comparison to NAND FLASH, but the cost is more for persistent memory. What do you think on the usability for this technology in future?

A. Very good. See this presentation “MRAM, XPoint, ReRAM PM Fuel to Propel Tomorrow’s Computing Advances” by analysts, Tom Coughlin and Jim Handy for an in-depth treatment.

Q. Does PM have a ‘lifespan’ similar to SSDs (e.g. 3 years with heavy writes, 5 years)?

A. Yes, but that will vary by device technology and manufacturer. We expect the endurance to be very high; comparable or better than the best of flash technologies.

Q. What is the performance difference between fast SSD vs “PM as DAX?”

A. As you might expect us to say; it depends. PM via DAX is meant as a bridge to using PM natively, but you might expect to have improved performance from PM over NVMe as compared with a flash based SSD, as the latency of PM is much lower than flash; micro-seconds as opposed to low milliseconds.

Q. Does DAX work the same as SSDs?

A. No, but it is similar. DAX enables efficient block operations on PM similar to block operations on an SSD.

Q. Do we have any security challenges with PME?

A. Yes, and JEDEC is addressing them. Also see the Security Threat Model presentation here.

Q. On the presentation slide of what is or is not persistent memory, are you saying that in order for something to be PM it must follow the SNIA persistent memory programming model? If it doesn’t follow that model, what is it?

A. No, the model is a way of consuming this new technology. PM is anything that looks like memory (it is byte addressable via CPU load and store operations) and is persistent (it doesn’t require any external power source to retain information).

Q. DRAM is basically a capacitor. Without power, the capacitor discharges and so the data is volatile. What exactly is persistent memory? Does it store data inside DRAM or it will use FLASH to store data?

A. The presentation discusses two types of NVDIMM; one is based on DRAM and a flash backup that provides the persistence (that is NVDIMM-N), and the other is based on PM technologies (that is NVDIMM-P) that are themselves persistent, unlike DRAM.

Q. Slide 15: If Persistent memory is fast and can appear as byte-addressable memory to applications, why bother with PM needing to be block addressed like disks?

A. Because it’s going to be much easier to support applications from day one if PM can be consumed like very fast disks. Eventually, we expect PM to be consumed directly by applications, but that will require them to be upgraded to take advantage of it.

Q. Can you please elaborate on byte and block addressable?

A. Block addressable is the way we do I/O; that is, data is read and written in large blocks of data, typically 4Kbytes in size. Disk interfaces like SCSI or NVMe take commands to read and write these blocks of data to the external device by transferring the data to and from CPU memory, normally DRAM. Byte addressable means that we’re not doing any I/O at all; the CPU instructions for loading & storing fast registers from memory are used directly on PM. This removes an entire software stack to do the I/O, and means we can efficiently work on much smaller units of data; down to the byte as opposed to the fixed 4Kb demanded by I/O interfaces. You can learn more in our presentation “File vs. Block vs. Object Storage.”

There are now 10 installments of the “Too Proud to Ask” webcast series, covering these topics:

If you have an idea for an “Everything You Wanted to Know about Storage, but were too Proud to Ask” presentation, please let comment on this blog and the NSF team will put it up for consideration.

Networking Questions for Ethernet Scale-Out Storage

Fred Zhang Leave a comment

Unlike traditional local or scale-up storage, scale-out storage imposes different and more intense workloads on the network. That’s why the SNIA Networking Storage Forum (NSF) hosted a live webcast “Networking Requirements for Ethernet Scale-Out Storage.” Our audience had some insightful questions. As promised, our experts are answering them in this blog.

Q. How does scale-out flash storage impact Ethernet networking requirements?

A.  Scale-out flash storage demands higher bandwidth and lower latency than scale-out storage using hard drives. As noted in the webcast, it’s more likely to run into problems with TCP Incast and congestion, especially with older or slower switches. For this reason it’s more likely than scale-out HDD storage to benefit from higher bandwidth networks and modern datacenter Ethernet solutions–such as RDMA, congestion management, and QoS features.

Q. What are your thoughts on NVMe-oF TCP/IP and availability?

A.  The NVMe over TCP specification was ratified in November 2018, so it is a new standard. Some vendors already offer this as a pre-standard implementation. We expect that several of the scale-out storage vendors who support block storage will support NVMe over TCP as a front-end (client connection) protocol in the near future. It’s also possible some vendors will use NVMe over TCP as a back-end (cluster) networking protocol.

Q. Which is better: RoCE or iWARP?

A.  SNIA is vendor-neutral and does not directly recommend one vendor or protocol over another. Both are RDMA protocols that run on Ethernet, are supported by multiple vendors, and can be used with Ethernet-based scale-out storage. You can learn more about this topic by viewing our recent Great Storage Debate webcast “RoCE vs. iWARP” and checking out the Q&A blog from that webcast.

Q. How would you compare use of TCP/IP and Ethernet RDMA networking for scale-out storage?

A.  Ethernet RDMA can improve the performance of Ethernet-based scale-out storage for the front-end (client) and/or back-end (cluster) networks. RDMA generally offers higher throughput, lower latency, and reduced CPU utilization when compared to using normal (non-RDMA) TCP/IP networking. This can lead to faster storage performance and leave more storage node CPU cycles available for running storage software. However, high-performance RDMA requires choosing network adapters that support RDMA offloads and in some cases requires modifications to the network switch configurations. Some other types of non-Ethernet storage networking also offer various levels of direct memory access or networking offloads that can provide high-performance networking for scale-out storage.

Q. How does RDMA networking enable latency reduction?

A. RDMA typically bypasses the kernel TCP/IP stack and offloads networking tasks from the CPU to the network adapter. In essence it reduces the total path length which consequently reduces the latency. Most RDMA NICs (rNICs) perform some level of networking acceleration in an ASIC or FPGA including retransmissions, reordering, TCP operations flow control, and congestion management.

Q. Do all scale-out storage solutions have a separate cluster network?

A.  Logically all scale-out storage systems have a cluster network. Sometimes it runs on a physically separate network and sometimes it runs on the same network as the front-end (client) traffic. Sometimes the client and cluster networks use different networking technologies.

 

 

 

 

Storage Expert Takes on Hyperconverged Questions

John Kim 1 Comment

Last month, we were fortunate enough to have Greg Schulz, analyst and founder of Server Storage IO, as a guest speaker at our SNIA Ethernet Storage Forum webcast, “What Does Hyperconverged Mean to Storage.” If you missed it, it’s now available on-demand. Greg fielded many great questions during the live event, but we didn’t have time to get to them all. So here they are:

Q. What is the difference between Converged Infrastructure (CI) and Hyperconverged Infrastructure (HCI)?

A. HCI is aggregated. You scale compute and storage in lock step. Converged is disaggregated. You can scale the compute independently of the storage. There are some software solutions that can support both hyper-converged (aggregated) and converged (disaggregated) deployments.

 Q.  What is your definition of “Little Data”?

A. Little Data is anything that’s not Big Data. It encompasses traditional databases, traditional structured, semi-structured and even some unstructured data.

Q. With convergence, what is the impact on the IT organization?

A. There is an opportunity for organizations to converge how they manage data infrastructure resources and services delivery. In other words, the technology can be leveraged to help an organization itself converge. Another impact is how converged solutions are protected, backed up, BC/BR/DR and related management done. Traditionally there are separate IT teams for compute, storage, and networking, especially in a large organization. New technology solutions may allow an organization to converge those teams.

Q. Is there a hybrid strategy? Where a complete information system is composed of HCI/CI building blocks? If yes, what management tools would span these components?

A. Sure, why not? Certainly you can converge your environment into a particular CI/HCI solution or approach, likewise, different CI/HCI solutions can co-exist along with other solutions in a given environment in hybrid ways. Have a hybrid strategy that looks at how technologies and solutions adapt to your needs and environment. Focus on how it’s going to work for you, vs. you having to work for them.

Q. What does FUZE stand for?

A. FUZE is not an acronym. It is the actual fuzing as in melding and bringing together things – literally fuzing thing together.

Q. Do HCI vendors re-balance (compute, I/O, storage) automatically as more nodes are added?

A. Solutions vary in how they rebalance the workloads. Some are dynamic while others rebalance on intervals; it varies how, when and what they rebalance. So, as you add capacity as you make changes, you need to make sure resources are properly allocated to address performance.

Q. Can’t you offload those CPU cycles caused by I/O to another CPU?

A. That’s an interesting question. Yes, move the application to another CPU. There is software that will leverage the resources on another CPU. Most HCI and CI solutions are running on a stack that requires hardware somewhere.

Q. This discussion has touched on compute and storage scaling. What about network between compute in the CI/HCI infrastructure and external to other compute, databases, or end-users?

A. Both CI and HCI need to connect to other resources, but in most cases the highest levels of network traffic are inside the CI or HCI stack because the compute and storage resources are contained within. Their connections to outside clients or servers data exchange, application integration, or client access is important but usually not very demanding on network bandwidth. (External connections for storage remote replication or backup could be bandwidth-intensive.)

Q. How can the current Enterprise Storage Products blend with either CI or HCI? Enterprise Storage is basically centralized storage architecture however the HCI is built mostly on ‘distributed storage architecture’. So how can current Enterprise Storage show use cases to the customer to sell their Enterprise Storage either as part of the HCI solution or exist along with HCI?

A. Generally enterprise storage products can be included in CI but are not blended with HCI. For example Dell EMC, Cisco (with NetApp and other storage vendors), IBM and Oracle offer CI solutions that include enterprise storage arrays in the rack. Most HCI platforms do not interoperate with enterprise storage arrays because the HCI platforms include their own storage. They can co-exist with enterprise storage arrays and that’s how most customers deploy them—some workloads run on the HCI infrastructure while others continue to use enterprise storage arrays.

Q. One of the HCI selling points is simplicity and cost reductions from a la carte. It seems that from what is being presented, that may not be the case. Can you elaborate on where HCI may become more complex, costly?

A. It comes down to value. You can buy all the components yourself and glue them all together and may come up with a lower total cost, but what is the value of your time? What is the cost of staff time to evaluate, test, deploy and maintain. The total value must be considered. It’s possible that HCI will be more costly than a disaggregated deployment that separates compute and storage, but this depends heavily on the workload and specific vendor product solution implementation.

Q. Current HCI “full stack” solutions claim compute and storage convergence, but what about the network? Given the east/west traffic introduced by HCI solutions, what networking solutions should customers be looking at?

A. Most of the common HCI solutions are packaged with server, storage, compute and most have networking included as well—typically the network adapters and sometimes also the switches. Some even have a backend software defined networking (SDN) capability as part of their stack.

Q. Related to HCI answer, what about vendors who allow for storage growth and/or server (compute) and storage additions. This allows for aggregated and dis-aggregated…yes?

A. Most HCI vendors require compute and storage to be added simultaneously, though many support different nodes with different ratios of compute and storage. This allow customers to change the ratio of compute and storage by adding different node types. And yes, some HCI vendors also support both a hyper-converged and disaggregated model, with the disaggregated model allowing compute and storage to be added separately.

Q. What are the tools available to make HCI work in a hybrid load environment, with different workload requirements, e.g.: VDI and Databases?

A. There are tools for moving and migrating applications, workloads, systems and VMs into CI/HCI environments, likewise for tuning, optimizing, gaining insight, analytics and reporting. Most of the CI/HCI solutions have tools built into them for optimizing PACE (Performance, Availability, Capacity, Economics) attributes along with server compute, memory, storage, and I/O resources. Some CI/HCI solutions are optimized for VDI/workspaces, while others are able to support general workloads including databases, and some even support HPC/SC or other specialized workloads.

Q. Does network performance affect HCI or CI performance?

A. Sometimes. Most hybrid HCI nodes are happy with the bandwidth of 10GbE, but if the nodes are all-flash or have many disks, then a faster speed may be required to avoid a network bottleneck. Network latency could affect HCI or CI performance in some cases, especially with all-flash storage. Of course a reliable network helps ensure reliable CI/HCI operations.

Update: If you missed the live event, it’s now available  on-demand. You can also  download the webcast slides.

Latency Budgets for Solid State Storage Access

J Metz Leave a comment

New solid state storage technologies are forcing the industry to refine distinctions between networks and other types of system interconnects.   The question on everyone’s mind is: when is it beneficial to use networks to access solid state storage, particularly persistent memory?

It’s not quite as simple as a “yes/no” answer. The answer to this question involves application, interconnect, memory technology and scalability factors that can be analyzed in the context of a latency budget.

On April 19th, Doug Voigt, Chair SNIA NVM Programming Model Technical Work Group, returns for a live SNIA Ethernet Storage Forum webcast, “Architectural Principles for Networked Solid State Storage Access – Part 2” where we will explore latency budgets for various types of solid state storage access.  These can be used to determine which combinations of interconnects, technologies and scales are compatible with Load/Store instruction access and which are better suited to IO completion techniques such as polling or blocking.

In this webcast you’ll learn:

  • Why latency is important in accessing solid state storage
  • How to determine the appropriate use of networking in the context of a latency budget
  • Do’s and don’ts for Load/Store access

This is a technical seminar built upon part 1 of this series. If you missed it, you can view it on demand at your convenience. It will give you a solid foundation on this topic, outlining key architectural principles that allow us to think about the application of  networked  solid state technologies more systematically.

I hope you will register today for the April 19th event. Doug and I will be on hand to answer questions on the spot.

Update: If you missed the live event, it’s now available  on-demand. You can also  download the webcast slides.

Clearing Up Confusion on Common Storage Networking Terms

J Metz Leave a comment

Do you ever feel a bit confused about common storage networking terms? You’re not alone. At our recent SNIA Ethernet Storage Forum webcast “Everything You Wanted To Know About Storage But Were Too Proud To Ask – Part Mauve,” we had experts from Cisco, Mellanox and NetApp explain the differences between:

  • Channel vs. Busses
  • Control Plane vs. Data Plane
  • Fabric vs. Network

If you missed the live webcast, you can watch it on-demand. As promised, we’re also providing answers to the questions we got during the webcast. Between these questions and the presentation itself, we hope it will help you decode these common, but sometimes confusing terms.

And remember, the “Everything You Wanted To Know About Storage But Were Too Proud To Ask” is a webcast series with a “colorfully-named pod” for each topic we tackle. You can register now for our next webcast: Part Teal, The Buffering Pod, on Feb. 14th.

Q. Why do we have Fibre and Fiber

A. Fiber Optics is the term used for the optical technology used by Fibre Channel Fabrics.   While a common story is that the “Fibre” spelling came about to accommodate the French (FC is after all, an international standard), in actuality, it was a marketing idea to create a more unique name, and in fact, it was decided to use the British spelling – “Fibre”.

Q. Will OpenStack change all the rules of the game?

A. Yes. OpenStack is all about centralizing the control plane of many different aspects of infrastructure.

Q. The difference between control and data plane matters only when we discuss software defined storage and software defined networking, not in traditional switching and storage.

A. It matters regardless. You need to understand how much each individual control plane can handle and how many control planes you have from a overall management perspective. In the case were you have too many control planes SDN and SDS can be a benefit to you.

Q. As I’ve heard that networks use stateless protocols, would FC do the same?

A.  Fibre Channel has several different Classes, which can be either stateful or stateless. Most applications of Fibre Channel are Class 3, as it is the preferred class for SCSI traffic, A connection between Fibre Channel endpoints is always stateful (as it involves a login process to the Fibre Channel fabric). The transport protocol is augmented by Fibre Channel exchanges, which are managed on a per-hop basis. Retransmissions are handled by devices when exchanges are incomplete or lost, meaning that each exchange is a stateful transmission, but the protocol itself is considered stateless in modern SCSI-transport Fibre Channel.

iSCSI, as a connection-oriented protocol, creates a nexus between an initiator and a target, and is considered stateful.  In addition, SMB, NFSv4, ftp, and TCP are stateful protocols, while NFSv2, NFSv3, http, and IP are stateless protocols.

Q. Where do CIFS/SMB come into the picture?

A. CIFFS/SMB is part of a network stack.   We need to have a separate talk about network stacks and their layers.   In this presentation, we were talking primarily about the physical layer of the networks and fabrics.   To overly simplify network stacks, there are multiple layers of protocols that run on top of the physical layer.   In the case of FC, those protocols include the control plane protocols (such as FC-SW), and the data plane protocols.   In FC, the most common data plane protocol is FCP (used by SCSI, FICON, and FC-NVMe).   In the case of Ethernet, those protocols also include the control plan (such as TCP/IP), and data plane protocols.   In Ethernet, there are many commonly used data plane protocols for storage (such as iSCSI, NFS, and CIFFS/SMB)

Update: If you missed the live event, it’s now available  on-demand. You can also  download the webcast slides.

Ethernet Roadmap for Networked Storage Q&A

David Fair Leave a comment

Almost 200 people attended our joint Webcast with the Ethernet Alliance: “The 2015 Ethernet Roadmap for Networked Storage.” We had a lot of great questions during the live event, but we did not have time to answer them all. As promised, we’ve complied answers for all of the questions that came in. If you think of additional questions, please feel free to comment on this blog.

Q. What did you mean by parity of flash with HDD?

A. We were referring to the O’Reilly article in “Network Computing.”   O’Reilly is predicting parity in BOTH capacity and price in 2016.

Q. When do we expect IEEE standards ratification for 25G speed?

A. 2016.   You can see the exact schedule here.

Q. Do you envision the Enterprise, Cloud Providers, HPC, Financials getting rid of their 10/40GbE infrastructure and replacing that with 25/100GbE infrastructure in 2017? Will these customers deploy 100GbE/25GbE switch in the leaf layer in 2017?

A. Deployment will occur over a multi-year time span overall if only because switch infrastructure is expensive to upgrade, as reflected in the Crehan Research forecast.   New deployments will likely move to 25/100GbE as new switches with 100GbE downstream ports become available in 2016.     Just because the Cloud Service Providers are currently the most aggressive in driving new infrastructure purchases, they represent the largest early volumes for 25/100 GbE.   Enterprise is still in the midst of the transition from 1GbE to 10GbE.

Q. What are some of the developments on spanning-tree derivatives vs. Dykstra based derivatives such as OSPF, FSPF for switches?

A. Beyond the scope of this presentation on Ethernet.   Ethernet is defined by the IEEE for L1 and L2 in the ISO model.   Your questions are at L3 and L4, which is handled by organizations like IETF.

Q. With all the speeds possible who is working on flow control?

A. Flow control at the 802.1 level is supported in the Layer 1/2 PHY & MAC by setting upper bounds on the delay through each layer which allows higher layers to comprehend the delays & response times to pause frames. Each new speed & PHY in 802.3 is accompanied by delay constraint specifications to support this.

Q.   Do you have an overlay graphic that shows the Ethernet RDMA roadmap?   If so, is Ethernet storage the primary driver for that technology?

A.   Beyond the scope of this presentation on Ethernet.   Ethernet is defined by the IEEE for L1 and L2 in the ISO model.   Your questions are at L3 and L4, which is handled by organizations like IETF and the InfiniBand Trade Association.

Q. The adoption of faster and new Ethernet always has to do with the costs of acquiring new technology. How long do you think it will take to adopt/acquire faster Ethernet in datacenters now that the development is happening much faster than the last 20 years?

A. Please see the chart on slide 7 where Crehan Research predicts how fast the technology will diffuse into deployments.

Q. What do you expect as cost comparison between Ethernet and InfiniBand going forward?
Also, what work is being done to reduce latency?

A. Beyond the scope of this presentation.   Latency is primarily a consequence of design methodologies and semiconductor process technology, and thus under the control of the silicon device manufacturers.   Some vendors prioritize latency more than others.

Q. What’s the technical limitation as speeds go higher and higher?

A. A number of factors limit speeds going faster and faster, but the main problem is that materials attenuate signals as they travel at higher frequencies.

Q. Will 1GbE used for manageability purposes disappear from public cloud? If so, what is the expected time frame?

A. This is a choice for end users.   Most equipment is managed on a separate network for security concerns, but users can eliminate these management networks at any time.

Q. What are the relative market size predictions for the expanding number of standards (25G, 50G, 100G, 200G, etc.)?

A. See the Crehan Research forecast in the presentation.

Q. What is the major difference between SMF & MMF for the not so initiated?

A. The SMF has a 9um core while the MMF has a 50um core.   Different lasers are used for each fiber type and MMF typically goes 100 meters above 10GbE and SMF goes from 500m to 10km.

Q. Will 25G be available through both copper and fibre connectivity?

A. Yes.   IEEE 802.3 work is currently underway to specify 25Gb/s on twinax (“direct attach copper)” to 5 meters, printed circuit backplane up to ~1m, twisted pair copper to 30m, multimode fiber to 100m.   There is no technology barrier to 25G on SMF, just that a standards project to specify it has not started yet.

Q. This is interesting from a hardware viewpoint, but has nothing to do with storage yet.   Are we going to get to how this relates to storage other than saying flash drives are fast and only Ethernet can keep up?

A. Beyond the scope of this presentation on Ethernet.   Ethernet is defined by the IEEE for L1 and L2 in the ISO model.   Your questions are directed at the higher layers.   The key point of this webcast is that storage networking engineers need to pay much more attention to the Ethernet roadmap than they have historically, primarily because of NVM.

Q. How does “SFP 28” fit in this mix?   Is it required for 25G?

A. SFP28 connectors and modules are required for 25GbE because they give better performance than SFP+ that only works to 10GbE.

Q. Can you provide the quick difference between copper & optical on speed & costs?

A. Copper and optical Ethernet links are usually standardized at the same speed.   400GbE is not defining a copper link but an active Direct Attached Cable (DAC) will probably support 400GbE.   Cost depends on volume and many factors and is beyond the scope of this presentation.   Copper is usually a fraction of the cost of optical links.

Q. Do you think people will try to use multiple CAT 5e to get more aggregate bandwidth to the access points to avoid having to run Fibre to them?

A. IEEE is defining 2.5GBASE-T and 5GBASE-T to enable Cat5e to support faster wireless access points.

Q. When are higher speeds and PoE going to reach the point when copper based Ethernet will become a viable heat source for buildings thus helping the environment?

A. 🙂   IEEE is defining 4 wire PoE to deliver at least 60W to end devices.   You can find out more here.

Q. What are the use cases for 2.5Gb and 5.0Gb Base-T?

A. The leading use case for 2.5G/5GBASE-T is to provide the uplink for wireless LAN access points that support 802.11ac and future wireless technology.   Wireless LAN technology has advanced to the point where >1Gb/s BW is needed upstream from the AP, and 2.5G/5G provide a higher speed uplink while preserving the user’s investment in Cat5e/Cat6 cabling.

Q. Why not have only CFP2 sockets right away with things disabled for lower speeds for all the intervening years leading to full-fledged CFP2?

A. CFP2 is defined for 100GbE and 8 ports can be used on a 1U switch. 100GbE switches are shifting to QSFP28 so that 32 ports of 100GbE is supported in a 1U switch at low cost.   The CFP2 is much more expensive than QSFP28 and will not be used for lower speeds because of the high cost.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Life of a Storage Packet

J Metz Leave a comment

Keeping storage as close to the application as possible and reasonable is important, but different types of storage can make a big difference for performance as well as types of workloads. Starting with the basics and working to more complexity, find out how storage really works in this first of the Packet Walk series of the “Napkin Dialogues” series. Warning: You’re on your own when tipping the pizza delivery person!

Download (PDF, 1.71MB)